Module java.desktop

Package javax.swing

Interface BoundedRangeModel

All Known Implementing Classes:

DefaultBoundedRangeModel

public interface BoundedRangeModel

Defines the data model used by components like Sliders and ProgressBars. Defines four interrelated integer properties: minimum, maximum, extent and value. These four integers define two nested ranges like this:

 minimum <= value <= value+extent <= maximum
 

The outer range is minimum,maximum and the inner range is value,value+extent. The inner range must lie within the outer one, i.e. value must be less than or equal to maximum and value+extent must greater than or equal to minimum, and maximum must be greater than or equal to minimum. There are a few features of this model that one might find a little surprising. These quirks exist for the convenience of the Swing BoundedRangeModel clients, such as Slider and ScrollBar.

• The minimum and maximum set methods "correct" the other three properties to accommodate their new value argument. For example setting the model's minimum may change its maximum, value, and extent properties (in that order), to maintain the constraints specified above.
• The value and extent set methods "correct" their argument to fit within the limits defined by the other three properties. For example if value == maximum, setExtent(10) would change the extent (back) to zero.
• The four BoundedRangeModel values are defined as Java Beans properties however Swing ChangeEvents are used to notify clients of changes rather than PropertyChangeEvents. This was done to keep the overhead of monitoring a BoundedRangeModel low. Changes are often reported at MouseDragged rates.

For an example of specifying custom bounded range models used by sliders, see Separable model architecture in A Swing Architecture Overview.

Since:

1.2

See Also:

DefaultBoundedRangeModel

Method Summary

Modifier and Type	Method	Description
void	addChangeListener(ChangeListener x)	Adds a ChangeListener to the model's listener list.
int	getExtent()	Returns the model's extent, the length of the inner range that begins at the model's value.
int	getMaximum()	Returns the model's maximum.
int	getMinimum()	Returns the minimum acceptable value.
int	getValue()	Returns the model's current value.
boolean	getValueIsAdjusting()	Returns true if the current changes to the value property are part of a series of changes.
void	removeChangeListener(ChangeListener x)	Removes a ChangeListener from the model's listener list.
void	setExtent(int newExtent)	Sets the model's extent.
void	setMaximum(int newMaximum)	Sets the model's maximum to newMaximum.
void	setMinimum(int newMinimum)	Sets the model's minimum to newMinimum.
void	setRangeProperties(int value, int extent, int min, int max, boolean adjusting)	This method sets all of the model's data with a single method call.
void	setValue(int newValue)	Sets the model's current value to newValue if newValue satisfies the model's constraints.
void	setValueIsAdjusting(boolean b)	This attribute indicates that any upcoming changes to the value of the model should be considered a single event.

Method Detail

getMinimum

int getMinimum()

Returns the minimum acceptable value.

Returns:

the value of the minimum property

See Also:

setMinimum(int)

setMinimum

void setMinimum(int newMinimum)

Sets the model's minimum to newMinimum. The other three properties may be changed as well, to ensure that:

 minimum <= value <= value+extent <= maximum
 

Notifies any listeners if the model changes.

Parameters:

newMinimum - the model's new minimum

See Also:

getMinimum(), addChangeListener(javax.swing.event.ChangeListener)

getMaximum

int getMaximum()

Returns the model's maximum. Note that the upper limit on the model's value is (maximum - extent).

Returns:

the value of the maximum property.

See Also:

setMaximum(int), setExtent(int)

setMaximum

void setMaximum(int newMaximum)

Sets the model's maximum to newMaximum. The other three properties may be changed as well, to ensure that

 minimum <= value <= value+extent <= maximum
 

Notifies any listeners if the model changes.

Parameters:

newMaximum - the model's new maximum

See Also:

getMaximum(), addChangeListener(javax.swing.event.ChangeListener)

getValue

int getValue()

Returns the model's current value. Note that the upper limit on the model's value is maximum - extent and the lower limit is minimum.

Returns:

the model's value

See Also:

setValue(int)

setValue

void setValue(int newValue)

Sets the model's current value to newValue if newValue satisfies the model's constraints. Those constraints are:

 minimum <= value <= value+extent <= maximum
 

Otherwise, if newValue is less than minimum it's set to minimum, if its greater than maximum then it's set to maximum, and if it's greater than value+extent then it's set to value+extent.

When a BoundedRange model is used with a scrollbar the value specifies the origin of the scrollbar knob (aka the "thumb" or "elevator"). The value usually represents the origin of the visible part of the object being scrolled.

Notifies any listeners if the model changes.

Parameters:

newValue - the model's new value

See Also:

getValue()

setValueIsAdjusting

void setValueIsAdjusting(boolean b)

This attribute indicates that any upcoming changes to the value of the model should be considered a single event. This attribute will be set to true at the start of a series of changes to the value, and will be set to false when the value has finished changing. Normally this allows a listener to only take action when the final value change in committed, instead of having to do updates for all intermediate values.

Sliders and scrollbars use this property when a drag is underway.

Parameters:

b - true if the upcoming changes to the value property are part of a series

getValueIsAdjusting

boolean getValueIsAdjusting()

Returns true if the current changes to the value property are part of a series of changes.

Returns:

the valueIsAdjustingProperty.

See Also:

setValueIsAdjusting(boolean)

getExtent

int getExtent()

Returns the model's extent, the length of the inner range that begins at the model's value.

Returns:

the value of the model's extent property

See Also:

setExtent(int), setValue(int)

setExtent

void setExtent(int newExtent)

Sets the model's extent. The newExtent is forced to be greater than or equal to zero and less than or equal to maximum - value.

When a BoundedRange model is used with a scrollbar the extent defines the length of the scrollbar knob (aka the "thumb" or "elevator"). The extent usually represents how much of the object being scrolled is visible. When used with a slider, the extent determines how much the value can "jump", for example when the user presses PgUp or PgDn.

Notifies any listeners if the model changes.

Parameters:

newExtent - the model's new extent

See Also:

getExtent(), setValue(int)

setRangeProperties

void setRangeProperties(int value,
                        int extent,
                        int min,
                        int max,
                        boolean adjusting)

This method sets all of the model's data with a single method call. The method results in a single change event being generated. This is convenient when you need to adjust all the model data simultaneously and do not want individual change events to occur.

Parameters:

value - an int giving the current value

extent - an int giving the amount by which the value can "jump"

min - an int giving the minimum value

max - an int giving the maximum value

adjusting - a boolean, true if a series of changes are in progress

See Also:

setValue(int), setExtent(int), setMinimum(int), setMaximum(int), setValueIsAdjusting(boolean)

addChangeListener

void addChangeListener(ChangeListener x)

Adds a ChangeListener to the model's listener list.

Parameters:

x - the ChangeListener to add

See Also:

removeChangeListener(javax.swing.event.ChangeListener)

removeChangeListener

void removeChangeListener(ChangeListener x)

Removes a ChangeListener from the model's listener list.

Parameters:

x - the ChangeListener to remove

See Also:

addChangeListener(javax.swing.event.ChangeListener)